1. Field of the Invention
The present invention relates to a mold for a gasket, a method of manufacturing a gasket and a gasket in accordance with a sealing technique.
2. Description of the Conventional Art
As one kind of an endless-shaped gasket, there has been conventionally known widely an O-ring formed as a planar circular ring shape, and the O-ring is formed in various sizes in correspondence to a product specification.
In the case of molding a large-diameter O-ring with the size of a diameter over 1600 mm for example, a size of a used mold comes to 2000 mm in length of one side thereof if it is intended to integrally mold the whole O-ring while keeping a product shape as it is, so that a manufacturing facility is extremely enlarged in size.
Further, there has been developed a method for carrying out a joining work after molding one O-ring divisionally in a circumferential direction, however, in accordance with this method, it takes a lot of labor and time for manufacturing, and concavity and convexity are generated at joint parts of the mold products, so that a lack of strength tends to be caused.
Reference is made to Japanese Unexamined Patent Publication No. 9-193170, Japanese Unexamined Patent Publication No. 10-138254 and Japanese Unexamined Patent Publication No. 10